Why is Lord Shiva called आशुतोष (ĀśuToṣa) ?
In Sanskrit, Āśu (आशु) means quick and Toṣa (तोष) means satisfaction or pleasure. Lord shiva is the one deity who is the one who is easily pleased. Unlike many other deities, Shiva does not require rituals. All he needs is sincere devotion done with pure heart.
Why is shiva called भोलानाथ (Bholenath)?
Bhole (भोला) means innocent and Nath (नाथ) means lord. Lord Shiva is approachable for everyone and all he needs is pure devotion. He never demands big rituals and offerings.
In many ancient texts it is mentioned that Lord Shiva granted immense boons to asuras who performed severe penance. As he does not judge their motives. Asuras misuse their boons due to their egos and ignorance. The misuse of boons leads to the downfall of the asuras.
A boon is a divine blessing. Misusing boon for any selfish or destructive purpose is Adharm. Everyone has to face consequences if they choose to misuse their power.
Why is Lord Shiva called भूतनाथ (Bhūtanāth) ?
In Sanskrit, Bhūta (भूत) means elements, any living being or spirit. Nath (नाथ) means lord.
Five Elements which are known as Pancha maha Bhootas like पृथ्वी (Earth), आप (Water), तेज(Fire), वायू (Air) आणि आकाश (Ether). He is a master of these elements.
Another meaning is that he is the controller of all types of spirits. Also he is supreme master of all souls, meaning living beings, spirits as well as any creature.
ॐ नमः शिवाय